1. Field of the Invention
This invention relates to a heat exchanger and method for making a heat exchanger for use in an air conditioning system for vehicles, and more particularly, to a heat exchanger that allows for efficient and easy assembly.
2. Description of the Background Art
FIGS. 1 and 2 show a conventional heat exchanger used in an air conditioning system, for example, an evaporator or a condenser. In FIGS. 1 and 2, a heat exchanger comprises an upper tank 105, a lower tank 110 and heat exchanger core 115 disposed between the upper tank and the lower tank. The heat exchanger core 115 comprises a plurality of heat transfer tubes disposed parallel to one another. The upper tank 105 has an upper wall and a lower wall, which are connected to each other. The upper tank 105 is divided into three chambers by first partition plate 151 and second partition plate 152. First partition plate 151 and second partition plate 152 include respectively notched portions formed in the centers thereof. First partition plate 151 includes a plurality of holes therethrough. Lower tank 110 is divided into two chambers, such as first lower chamber and a second lower chamber, by partition plate 153. Further, the lower tank includes preventing overturn plate 154 therein. Preventing overturn plate 154 includes a notched portion formed in the center thereof and a plurality of holes therein. The number of holes formed in preventing overturn plate 154 as well as their respective diameter is determined so that a heat exchanger medium may pass freely through the holes. The lower wall of the upper tank 105 and the upper wall of the lower tank 110 are provided with a plurality of connection holes, respectively, for interconnecting a plurality of heat transfer tubes therebetween. An inlet pipe 210 and outlet pipe 220 are connected to the upper tank 105.
In assembling the upper tank 105 and the lower tank 110, first partition plate 151 is placed on the lower wall of the upper tank 105 so as to be located in the center of the lower wall of the upper tank 105 and second partition plate 152 is connected with first partition plate 151 at right angles to each other, so that the notched portion of second partition plate 152 fixedly inserts into the center notched portion of first partition plate 151 in an attempt to prevent movement and overturning during brazing. Further, in assembling the lower tank 110, partition plate 153 is placed on the lower wall of the lower tank 110 so as to be located in the center of the lower wall of the lower tank 110. In addition, preventing overturn plate 154 is connected with partition plate 153 at a right angle, so that the notched portion of partition plate 153 fixedly inserts into the center notched portion of the preventing overturn plate 154 to prevent movement and overturning during brazing. Finally, the heat exchanger may be placed in a brazing furnace, so that all of its parts may be brazed together.
In the arrangement described above, the partition plates 151 and 153 tend to fall down until they are connected with their corresponding partition plate 152 or the preventing overturn plate 154 respectively. Further, the partition plates 151, 152 and 153 and the preventing overturn plate 154 tend to incline and move from the desired location unless these parts are formed to extremely precise sizes.
In addition to the above problems, in prior art heat exchangers where partition plates and preventing overturn plates are not formed within very accurate size constraints, the partition plates and the preventing overturn plate often fail to connect with the upper tank 105 and the lower tank 110 during brazing because there exists a gap between the partition plates or preventing overturn plate and the walls of the upper tank 105 and the lower tank 110.
As a result of these problems, the brazing step of the assembly process is both complicated and time consuming. These factors cause a reduction in the overall operational productivity of the assembly process.